Functional screening of Alzheimer risk loci identifies PTK2B as an in vivo modulator and early marker of Tau pathology

Abstract

A recent genome-wide association meta-analysis for Alzheimer's disease (AD) identified 19 risk loci (in addition to APOE) in which the functional genes are unknown. Using Drosophila, we screened 296 constructs targeting orthologs of 54 candidate risk genes within these loci for their ability to modify Tau neurotoxicity by quantifying the size of >6000 eyes. Besides Drosophila Amph (ortholog of BIN1), which we previously implicated in Tau pathology, we identified p130CAS (CASS4), Eph (EPHA1), Fak (PTK2B) and Rab3-GEF (MADD) as Tau toxicity modulators. Of these, the focal adhesion kinase Fak behaved as a strong Tau toxicity suppressor in both the eye and an independent focal adhesion-related wing blister assay. Accordingly, the human Tau and PTK2B proteins biochemically interacted in vitro and PTK2B co-localized with hyperphosphorylated and oligomeric Tau in progressive pathological stages in the brains of AD patients and transgenic Tau mice. These data indicate that PTK2B acts as an early marker and in vivo modulator of Tau toxicity.

Regulation of the interaction between the neuronal BIN1 isoform 1 and Tau proteins – role of the SH3 domain

“…These data support the hypothesis that BIN1 might modulate the pathophysiological process involving Tau, a leading cause of neurodegeneration [13][14][15]. In addition, in a Drosophila melanogaster model overexpressing Tau, bin1 homologue Amph mediates Tau toxicity [11,16], and an increase in bin1 expression is observed in AD [11]. In addition, in a Drosophila melanogaster model overexpressing Tau, bin1 homologue Amph mediates Tau toxicity [11,16], and an increase in bin1 expression is observed in AD [11].…”

“…A functional variant modulating BIN1 expression is associated with neurofibrillary tangles, which are intraneuronal aggregates formed by abnormally phosphorylated Tau proteins [11]. In addition, in a Drosophila melanogaster model overexpressing Tau, bin1 homologue Amph mediates Tau toxicity [11,16], and an increase in bin1 expression is observed in AD [11]. However, this global pattern of expression may differ between the BIN1 isoforms: at the protein level in the brain of AD case, a decrease in BIN1Iso1 (the largest BIN1 isoform) was reported, whereas an increase in BIN1Iso9 (the shortest) was measured [17].…”

Large-scale transgenicDrosophilaresource collections for loss- and gain-of-function studies

“…Mutant animals or tissue-specific mosaics can be produced by simply crossing sgRNA-expressing flies to germline-specific Cas9 or somatic tissuespecific GAL4>Cas9 flies, respectively (Kondo and Ueda 2013;Port et al 2014;Port and Bullock 2016). A number of recent studies in Drosophila have used transgenic CRISPR for LOF, for example to identify novel modifiers of tauopathies (Butzlaff et al 2015;Dourlen et al 2017) or Parkinson's disease (Chen et al 2017;Rousseaux et al 2018); to model congenital disorders of glycosylation (Parkinson et al 2016); to identify genes that regulate tumorigenesis (Das et al 2013;Mishra-Gorur et al 2019); and to study inflammation and immunity (Lee et al 2018;Liu et al 2018).…”

Genetics of Alzheimer’s Disease: the Importance of Polygenic and Epistatic Components

“…SORL1 is intimately involved in the APP pathway, playing a role in the determination of APPs cleavage to Abeta [25]. PTK2B is a focal adhesion kinase, involved in cellular adhesion, expressed in the brain, and was also found to be an in vivo modulator of Tau toxicity [29]. MEF2C is also expressed in the cortex and known to be involved in the inflammation pathway; an assay of MEF2C binding sites was enriched in GWAS-implicated inflammation loci [30].…”